Tubular prostheses, such as stents, grafts, and stent-grafts are known for treating abnormalities in various passageways of the human body. In vascular applications, these devices often are used to replace or bypass occluded, diseased or damaged blood vessels such as stenotic or aneurysmal vessels. For example, it is well known to use stent-grafts of a biocompatible graft material supported by a framework, for e.g., one or more stent or stent-like structures, to treat or isolate aneurysms. The framework provides mechanical support and the graft material or liner provides a blood barrier. When implanting a stent-graft, the stent-graft typically is placed so that one end of the stent-graft is situated proximal to or upstream of the diseased portion of the vessel and the other end of the stent-graft is situated distal to or downstream of the diseased portion of the vessel. In this manner, the stent-graft extends through and spans the aneurysmal sac and extends beyond the proximal and distal ends thereof to replace or bypass the dilated wall.
Such tubular prostheses are known to be implanted in either an open surgical procedure or by a minimally invasive endovascular approach. Minimally invasive endovascular stent-grafts for use in treating aneurysms are often preferred over traditional open surgery techniques where the diseased vessel is surgically opened, and a graft is sutured into position bypassing the aneurysm. The endovascular approach generally involves opening a vein or artery with a needle, inserting a guidewire into the vein or artery through the lumen of the needle, withdrawing the needle, inserting over the guidewire a dilator located inside an associated sheath introducer having a hemostasis valve, removing the dilator and inserting a delivery catheter through the hemostasis valve and sheath introducer into the blood vessel. The delivery catheter with the stent-graft secured therein may then be routed through the vasculature to the target site. For example, a stent-graft delivery catheter loaded with a stent-graft can be percutaneously introduced into the vasculature, for e.g., into a femoral artery, and the stent-graft delivered endovascularly across an aneurysm where it is then deployed.
Specialized endovascular stent-grafts have been developed for the treatment of abdominal aortic aneurysm, hereinafter referred to as an AAA. An AAA is a bulge that forms in the wall of the abdominal aorta, which is the main vessel of the arterial system of the body that extends through the abdomen. An endovascular stent-graft for use in the abdominal aorta typically includes a number of self-expanding stent-graft segments that are assembled or mated within the patient to provide the finished stent-graft implant. The stent-graft implant may include a main stent-graft segment that constitutes a trunk section with two descending limb sections with the limb sections providing an anchoring point for subsequent endovascular placement of a right iliac limb stent-graft segment and a left iliac limb stent-graft segment of the stent-graft implant. Typically, the main stent-graft segment is delivered and implanted via a main delivery system that is withdrawn prior to respective branch delivery systems being introduced for delivery and implantation of each of the iliac limb stent-graft segments.
Although the endovascular approach is much less invasive, usually requiring less recovery time and involving less risk of complication as compared to open surgery, there can be concerns with anchoring and alignment of prostheses in relatively complex AAA applications such as ones involving branch vessels. The procedure becomes more complicated and the number of interventional devices needed to complete the procedure increases when more than one branch vessel is treated. For example, an AAA may occur having a proximal neck that is diseased or damaged to the extent that it cannot support an effective seal and connection with a prosthesis, such as is the case with short neck infrarenal, juxtarenal and surprarenal aneurysms. In some such presentations, a main stent-graft segment is provided with fenestrations or openings formed in its side wall below an upstream end thereof and in addition to iliac limb stent-graft segments being needed to complete the stent-graft implant, branch stent-graft segments are also used that extend between a respective fenestration of the main stent-graft segment and its branch vessel. To ensure alignment of the main stent-graft segment's fenestrations and the branch vessels, current techniques involve placing guidewires through each fenestration and branch vessel, e.g., each renal artery, prior to releasing the main stent-graft segment. Thereafter, branch delivery systems are introduced to deliver the branch stent-graft segments between the main stent-graft segment and the respective branch vessel with additional delivery systems then being introduced to deliver the iliac limb stent-graft segments between the main stent-graft segment and their respective vessels. A consequence of current treatments for AAA with the delivery of multiple stent-grafts that mate together to form a partial or complete implant are lengthy procedure times and the potential for patient harm that may be associated with delivery of the multiple interventional devices that are currently necessary to perform the delivery, positioning and assembly of the stent-graft segments.
What is needed in treating an AAA located at or about branch vessels is a simplified method for delivering the multiple mating stent-graft segments that eliminates procedure steps associated with the cannulation of mating features on the main stent-graft segment as well as a delivery system that can serve multiple functions to reduce the number of additional interventional devices needed to perform the procedure.